VB.NET Execute An Array of Array processes

Question

I've created an array of arrays and corresponding .bat files so I could execute them from VB.Net.

The main array consists of models as follows:

Priority1 models executables:
SWAT_0410003.exe
SWAT_0410004.exe
SWAT_0410008.exe
Priority2 models executables:
SWAT_0410005.exe
SWAT_0410006.exe
SWAT_0410007.exe
Priority3 models executables:
SWAT_04100009.exe

I want to call a process to execute the above models but I need for Priority1
to execute first.

Only when all executables in priority1 finished executing should priority2
execute and so on; Priority 2 needs input from Priority1, and priority3 needs input from Priority2...and so on.

There could be more than 3 priority levels.

How do I create and call processes so that they execute one after the other?

Appreciate any response.

Answer 1

Creating and calling processes sequentially is pretty straightforward. You just need to wait for the process to complete before continuing on.

Note: executing a process can be tricky especially if the process generates lots of output as you have to process the output buffer otherwise it'll deadlock. I'm ignoring all that here but to read about this issue go to the docs.

   ' Warning: My VB is rusty at best  
   Sub RunPrograms ( programs As String())   
      For Each program As String in programs  
         ' Use the appropriate Process.Start method for your needs, using the simplest one here  
         Dim process as Process = Process.Start(program)  
     
         ' Wait for it to exit, assuming it will not prompt for input or display so much data that the output buffer fills up  
         process.WaitForExit()  
     
         ' Optionally check the exit code  
        If process.ExitCode <> 0 Then  
            ' Something went wrong  
        End If  
      Next  
   End Sub  

If you need a Task-based approach then use WaitForExitAsync instead.

Now that you can execute a series of programs in sequential order you just need to add the priority to the list. For this it isn't clear how you modelled that so I'm going to envision that you have a simple type that assigns a priority to a program name.

   Public Class PriorityProgram  
   {  
       Public Property Priority As Integer  
       Public Property Program As String  
   }  

Now you can use LINQ to order your programs by priority first or group them.

   Sub ExecutePrograms ( programs As List(Of PriorityProgram) )  
      ' Group by priority and then it doesn't matter  
      Dim orderedPrograms = From program In programs  
                                              Group program By program.Priority into gr = Group  
                                              Select Priority, Programs = gr  
     
      For Each item In orderedPrograms  
          RunPrograms(item.Programs)  
      Next  
   End Sub